fix: 计重明细重量与托盘自重改为和恒定双向联动并校验非负

原逻辑托盘自重变化时重量同向增减，且修改重量不联动托盘自重。
改为两者之和恒等于接口初始值，修改任一方另一方反向同步变动；
任一方将小于 0 时拒绝输入、提示并回退显示。

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

module_base/src/main/java/com/lukouguoji/module_base/bean/GjcCheckInRecord.kt

@@ -3,6 +3,7 @@ package com.lukouguoji.module_base.bean
 import androidx.databinding.BaseObservable
 import androidx.databinding.Bindable
 import androidx.databinding.library.baseAdapters.BR
+import com.lukouguoji.module_base.ktx.showToast
 
 /**
  * 国际出港计重记录明细Bean
@@ -43,40 +44,76 @@ data class GjcCheckInRecord(
             }
         }
 
-    // 重量的字符串表示（用于双向绑定）
-    @get:Bindable
-    var weightStr: String
-        get() = if (weight == 0.0) "" else weight.toString()
-        set(value) {
-            val newWeight = value.toDoubleOrNull() ?: 0.0
-            if (weight != newWeight) {
-                weight = newWeight
-                notifyPropertyChanged(BR.weightStr)
-                onDataChanged?.invoke()
-            }
-        }
-
-    // 托盘自重编辑过程中的原始输入串（保持回显与输入一致，避免光标跳位）
-    // 不作为构造参数，data class copy 备份/恢复时自动丢弃，回退到 trayTotalWeight 显示
+    // 重量 / 托盘自重编辑过程中的原始输入串（保持回显与输入一致，避免光标跳位）
+    // 不作为构造参数，data class copy 备份/恢复时自动丢弃，回退到数值显示
     // @Transient：仅界面内部状态，不参与 Gson 序列化提交
+    @Transient
+    private var weightInput: String? = null
+
     @Transient
     private var trayTotalWeightInput: String? = null
 
-    // 托盘自重的字符串表示（用于双向绑定）
-    // 业务规则：重量包含托盘自重，托盘自重编辑后，重量同步增减相同差值
+    // 重量的字符串表示（用于双向绑定）
+    // 业务规则：重量 + 托盘自重 恒定（等于接口返回初始值之和），修改一方另一方反向同步变动
+    // 校验：任一方不能小于 0，非法输入直接拒绝并回退显示
     @get:Bindable
-    var trayTotalWeightStr: String
-        get() = trayTotalWeightInput
-            ?: if (trayTotalWeight == 0.0) "" else trayTotalWeight.toString()
+    var weightStr: String
+        get() = weightInput ?: if (weight == 0.0) "" else weight.toString()
         set(value) {
-            trayTotalWeightInput = value
-            val newTrayWeight = value.toDoubleOrNull() ?: 0.0
-            if (trayTotalWeight != newTrayWeight) {
-                weight = Math.round((weight + newTrayWeight - trayTotalWeight) * 100) / 100.0
-                trayTotalWeight = newTrayWeight
-                notifyPropertyChanged(BR.trayTotalWeightStr)
-                notifyPropertyChanged(BR.weightStr)
-                onDataChanged?.invoke()
+            val newWeight = value.toDoubleOrNull() ?: 0.0
+            val newTrayWeight = round2(weight + trayTotalWeight - newWeight)
+            when {
+                newWeight < 0 -> {
+                    showToast("重量不能小于 0")
+                    notifyPropertyChanged(BR.weightStr)
+                }
+                newTrayWeight < 0 -> {
+                    showToast("重量不能超过 ${round2(weight + trayTotalWeight)}，否则托盘自重将小于 0")
+                    notifyPropertyChanged(BR.weightStr)
+                }
+                else -> {
+                    weightInput = value
+                    if (weight != newWeight) {
+                        weight = newWeight
+                        trayTotalWeight = newTrayWeight
+                        trayTotalWeightInput = null
+                        notifyPropertyChanged(BR.weightStr)
+                        notifyPropertyChanged(BR.trayTotalWeightStr)
+                        onDataChanged?.invoke()
+                    }
+                }
             }
         }
+
+    // 托盘自重的字符串表示（用于双向绑定），联动规则同上
+    @get:Bindable
+    var trayTotalWeightStr: String
+        get() = trayTotalWeightInput ?: if (trayTotalWeight == 0.0) "" else trayTotalWeight.toString()
+        set(value) {
+            val newTrayWeight = value.toDoubleOrNull() ?: 0.0
+            val newWeight = round2(weight + trayTotalWeight - newTrayWeight)
+            when {
+                newTrayWeight < 0 -> {
+                    showToast("托盘自重不能小于 0")
+                    notifyPropertyChanged(BR.trayTotalWeightStr)
+                }
+                newWeight < 0 -> {
+                    showToast("托盘自重不能超过 ${round2(weight + trayTotalWeight)}，否则重量将小于 0")
+                    notifyPropertyChanged(BR.trayTotalWeightStr)
+                }
+                else -> {
+                    trayTotalWeightInput = value
+                    if (trayTotalWeight != newTrayWeight) {
+                        trayTotalWeight = newTrayWeight
+                        weight = newWeight
+                        weightInput = null
+                        notifyPropertyChanged(BR.trayTotalWeightStr)
+                        notifyPropertyChanged(BR.weightStr)
+                        onDataChanged?.invoke()
+                    }
+                }
+            }
+        }
+
+    private fun round2(v: Double): Double = Math.round(v * 100) / 100.0
 }